The invention relates to a cable clamp terminal for the connection of conducting cables to an electrical apparatus for instance to a circuit interrupter having a terminal block with two superposed housings or sockets, each of them disposed to receive the end of a cable and two set screws likely to be screwed into a tapped aperture of said block crosswise extending to said housings. The intermediate one of the screws tightens the cable inserted in the lower housing between the bottom and the intermediate screw and the other upper one tightens the cable inserted in the upper housing between the intermediate screw and the upper screw.
For certain applications it is necessary to connect to each terminal of an electrical apparatus, in particular of a high power circuit breaker with moulded casing, two cables or conducting wires. A connector in the form of a conducting block fastened on the connection lug of the circuit breaker and showing two juxtaposed holes meant for receiving connection cables was already suggested. The width of this terminal is too big for modern circuit breakers with moulded casing, and to remedy to this disadvantage, a superposed arrangement of two connecting cables was provided, for instance in the circuit breaker according to U.S. Pat. No. 3,355,685. In this case, it is necessary to provide an intermediate setscrew inserted between the two cables, to ensure a proper electrical connection between the cables and the terminal. The terminal being fastened to the circuit breaker lug, the lower cable was first introduced and the intermediate screw tightened wedging this cable against the terminal bottom. The second cable was then introduced and the upper screw comes and wedges the cable between the two screws. After mounting the intermediate screw is no longer accessible and it is then impossible to verify the right tightening of cables or to carryout a retightening taking up a certain stress relief or compression of the cable strands.
An object of the present invention is to remedy to this disadvantage and to permit the realization of a terminal of reduced width for the connection of two superposed conducting cables allowing a later retightening when the cables become loose in their sockets.
According to the present invention, the tapping of the intermediate screw shows a longitudinal play or clearance allowing a limited axial sliding of the intermediate screw fixed in rotation.
The tapping with play or clearance advantageously extends all along the length of the tapped aperture, the corresponding axial play of the two screws having no effect on the upper screw. The threading is advantageously of the square thread type to reduce in addition the side stresses exerted upon the terminal block.